Electrical switching device and contact spring set therefor

ABSTRACT

Mounting for contact springs of an electrical switching device. The springs are mounted at their inner ends in an insulating base member for the switching device and are freely movable at their free ends to alternately engage or disengage a stationary contact upon operation of an actuator for the springs. The mounting for each spring includes a stable flexing leg extending across the inner end of the spring and mounted in the base for the switch and having a right-angled portion extending parallel to the spring and mounted in a right-angled portion of the base for the switch. The stable flexing leg has a terminal extending therefrom through a window in the right-angled portion of the base. The stationary contact is mounted to extend between the contact springs and is flexible to a limited extent and fixed to an extension of the insulating base at its rear end and along one side of said contact. The stationary contact is diagonally slit in a longitudinal direction along the support portion of the base extending parallel to the contact, to accommodate a limited flexing of said stationary contact and may be drilled to vary the flexibility thereof and provide the required elasticity of said contact, and determine the bending point thereof.

United States Patent Aidn et al.

[ June 25, 1974 ELECTRICAL SWITCHING DEVICE AND CONTACT SPRING SETTHEREFOR Inventors: Martin Aidn; Alois Ruhland, both of Munich, GermanyAssignee: Siemens AB, Berlin, Germany Filed: Apr. 12, 1973 US. Cl.200/166 J, 200/1 A Int. Cl. I'I0lh l/28 Field of Search... 200/1 A, l R,166 J, 166 CT;

References Cited UNITED STATES PATENTS 5/l946 Wood 200/1 A l/l95lBellamy 200/l A X 7/1960 Hufnagel ZOO/i661 Primary Examiner-Robert K.Schaefer Assistant ExaminerWilliam J. Smith Attorney, Agent, orFirmHill, Gross, Simpson, Van Santcn, Steadman, Chiara & Simpson [5 7ABSTRACT Mounting for contact springs of an electrical switching device.The springs are mounted at their inner ends in an insulating base memberfor the switching device and are freely movable at their free ends toalternately engage or disengage a stationary contact upon operation ofan actuator for the springs. The mounting for each spring includes astable flexing leg extending across the inner end of the spring andmounted in the base for the switch and having a right-angled portionextending parallel to the spring and mounted in a right-angled portionof the base for the switch. The stable flexing leg has a terminalextending therefrom through a window in the right-angled portion of thebase. The stationary contact is mounted to extend between the contactsprings and is flexible to a limited extent and fixed to an extension ofthe insulating base at its rear end and along one side of said contact.The stationary contact is diagonally slit in a longitudinal directionalong the support portion of the base extending parallel to the contact,to accommodate a limited flexing of said stationary contact and may bedrilled to vary the flexibility thereof and provide the requiredelasticity of said contact, and determine the bending point thereof.

9 Claims, 5 Drawing Figures lii ELECTRICAL SWITCHING DEVICE AND CONTACTSPRING SET THEREFOR FIELD OF THE INVENTION Contact spring set forelectrical switching devices.

BACKGROUND, SUMMARY AND ADVANTAGES OF THE INVENTION In relays havingcontact spring sets arranged in layers, it has heretofore been necessaryto insert a relatively large portion of the length of each individualcontact spring in the insulation material of an insulating member orbase for the relay, to prevent the influences at the soldering lugs orterminals of the individual springs from being transferred to thecontact parts of the spring. This applies not only to contact springs inwhich the contact legs and soldering lugs or terminals run in the samedirection, but also applies where the soldering lug and contact springare at right angles with respect to each other. A contact spring set ofthis type is shown and described in DOS 2,016,903.

Due to the large clamping area required for the contact springs, suchsprings must be relatively long in order to achieve the necessaryeffective spring length. If, however, there is insufficient room in therelay housing for long contact springs, short contact springs with alarge spring constant, must be used in their place, which require highoperational forces.

Furthermore, in contact spring sets which are not in layers, and inwhich the individual springs are only inserted into slots in theinsulation material or base member for the relay, the requirements as tothe clamping length of the spring in the insulating material or base areno different than in the previously described contact springapplications. Where an effort is made to avoid this and the contactsprings are not injected into the insulation, but are subsequentlyclamped into guiding slots, corresponding large guiding angles arerequired for achieving good directional stability. This applies to thetype of contact spring described in DOS 2,038,879 in which the solderinglug runs at right angles to the contact leg. In this disclosure, inorder to achieve a stable mounting for the contact springs, thesoldering lug must also be anchored relatively deep in the insulationmaterial or base, and has the effect of increasing the overall height ofthe relay, which in many cases, is undesirable.

By the present invention, we affix a contact spring to an insulationbase in guiding slots of relatively low depth which serve as a stablemounting for the spring and attain this by providing at least two fixingedges for the contact spring in which at least one of these fixing edgesforms a mounting for a leg which basically runs parallel to the freelymovable contact spring.

By the use of a second fixing edge running generally parallel to thecontact spring and spaced from one side thereof, the contact spring isgiven good directional stability and exact spacing from the base andalso enables the spring structure to be adjustable. Moreover, with themounting just described, the parts of the contact springs which servefor fixing the spring to its insulating base can be kept very small inthe interest of a compact relay structure and the contact springs canhave a relatively large, effective spring length with a resultantminimum error constant. Thus, unavoidable production tolerances causeminimum differences in the force required to operate the spring andthereby enable the contact spring to be operated by a relatively lowoperating force.

In accordance with a preferred embodiment of the invention, two fixingedges are provided for each contact spring which run at right angles toeach other. This results in a generally L-shaped spring in which theseparation between the fixing leg of the spring and the contact leg canbe attained as by a deep cut or slot. The contact leg and the fixing legof the contact spring can be made in one piece, although where thespring is made from thin spring material, the fixing part or leg may bemade of a more stable material in a generally L-shaped form and rivetedor otherwise secured to the contact spring, and extend across and to oneside thereof. The fixing leg of the contact spring may also have asolder lug extending from one side thereof and running perpendicular tothe contact spring.

A principal advantage of the present invention is the provision of afirm insulating mounting for a contact spring, taking up a minor portionof the length of the spring.

Another advantage of the invention is that where the fixing of thecontact spring is in slots formed in the right-angled walls of a singleinsulating base, a firm holding of the fixing leg and contact spring isattained by the use of outwardly curved entrance walls within which thefixing edges of the spring extend.

A further advantage of the invention is that the flexibility of thecontact spring, free from its fixing leg, is attained by a slot betweenthe contact spring and fixing leg, one wall of which is parallel to theside wall of the contact spring and the other wall of which is at anangle and converges toward the contact spring to provide a desiredbending point of the spring which may be weakened in cross section andmay be increased or decreased in accordance with the requirements forflexibility of the contact spring for different switching conditions.

Other objects, features and advantages of the invention will be readilyapparent from the following description of a preferred embodimentthereof, taken in conjunction with the accompanying drawings, althoughvariations and modifications may be effected without departing from thespirit and scope of the novel concepts of the disclosure.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary view in sideelevation of a switch and contact spring arrangement constructed inaccordance with the principles of the present invention with certainparts broken away.

FIG. 1A is a fragmentary enlarged sectional view taken substantiallyalong line A-A of FIG. I, and illustrating the detailed structure of aclamping slot for one of the contact springs.

FIG. 2 is a fragmentary bottom plan view of the switching contact shownin FIG. 1, with certain parts broken away and with the clamping areas ofthe switching contact and its fixing leg shown by dotted sectionallines.

FIG. 3 is a view somewhat similar to FIG. 2, but showing a modified formof contact spring in which the contact spring and fixing leg are in onepiece; and

FIG. 4 is a detail view looking at the stationary contact from thebottom thereof and showing the clamping areas by dotted sectional lines.

DESCRIPTION OF PREFERRED FORM OF INVENTION In FIG. 1 of the drawings, wehave shown in side elevation a portion of an electrical switching deviceand contact spring set constructed in accordance with the principles ofthe present invention, and including a base member 1 made frominsulating material having two vertically spaced insulating slots 2formed therein for receiving and forming a mounting for the inner endsof contact springs 4. The base 1 has a central leg 1a extending betweenthe contact springs 4 in the direction of said springs and having agenerally U-shaped and widened outer end portion la, the legs of whichform a mounting for an insulating member 17 having a slot 3 extendingthereacross and forming a clamping area for receiving the rear endportion of an intermediate contact 5.

Each contact spring 4 extends along one side of a stable fixing leg 7forming a mounting therefor and curves upwardly from the leg 7 to a peakengaging a stationary abutment 40 between the ends of the spring andgradually curves downwardly from said peak to the end of the contactspring, to form a flexible contact leg 6, shown in FIG. 2 as having aslot 60 extending along the central portion thereof and dividing thecontact leg along its center to increase the flexibility thereof.Contacts 9 are riveted or otherwise secured to the inside of eachcontact leg 6 for engagement with contacts 9a riveted or otherwisesecured to opposite sides of the stationary contact 5. The gradualconverging of the contact leg from its opposite ends to a peak engagingthe abutment 4a biases the individual contact springs to engage themovable contacts 9 with the generally stationary contacts 9a.

The contacts 9 are disengaged from the contacts 9a by operation of arectilinearly movable shifter 8 having a lug 80 extending between thecontact springs and movable in opposite directions to disengage thecontacts 9 from the contacts 9a of one contact spring and accommodatethe engagement of the contacts 9 of the other contact spring with thecontacts 9a by the bias of the spring. The shifter 8 may be the armatureof a solenoid. This provides an alternately operable switching device inwhich contacts can be alternately made and broken by a simple shiftingoperation.

The insulating base 1 may be made from any suitable insulating materialand preferably may be made from a plastic insulating material, and isshown as having a back wall or end portion lb with a right-angledportion 10 projecting therefrom along the outsides of the contactsprings 4 and contact legs 6 of said springs. The right-angled portion10 may form a mounting for the abutments 4a, abutting the peakedportions of said springs, and biasing said contact springs to engage thecontacts 9 thereof with the contacts 9a on opposite sides of theintermediate generally stationary contact 5.

Each contact spring 4, as shown in FIG. 2, is made from a thin springcurrent conducting material, which may be phosphor-bronze or any othersuitable currentconducting, spring-like material and is welded orotherwise secured to a leg 70 of a fixing part 7 which with the contactspring 4 and leg 7a are anchored at their trailing ends in the slots 2,shown in FIG. 1A as having converging entering portions, converging tothe slots 2 having clamping areas 10 extending therealong.

The fixing leg 7 for each contact spring anchored along its leg 7a inthe slot 2 of the base 1, is generally L-shaped in cross section and hasa right-angled leg 7b anchored in an anchoring or clamping area 11 of aright-angled portion 1c of the base, extending parallel to the contactspring 4. The right-angled leg 7b of the fixing leg 7 has a terminal 12extending through the right-angled portion 10 and along the clampingarea 11. The terminal 12 may serve as a soldering lug or as a connectingplug and extends through a window or apertured portion of theright-angled portion 1c. The terminal 12 may be secured to theright-angled portion 10 and anchoring area 11, against withdrawal in anysuitable manner, which for example, may be by twisting of the terminalor molding the terminal within said wall to encapsulate the terminal insaid wall.

A firm mounting for the contact spring 4 has thus been provided,enabling free flexing of the spring and positively mounting the springin the base 1 at its extreme inner end portion, to enable the spring tohave a relatively large effective spring length with a small errorconstant.

In FIG. 3 of the drawings, we have illustrated a modification of theinvention in which each contact spring and fixing part 7 is in one pieceand clamped in the slot 2 of the clamping surface 10 and in a similarslot in a right-angled portion 1c forming the clamping area 11 for aportion 1b extending along said fixing or clamping area 11. A terminal12 extends outwardly from the portion 1b of the fixing area 11 of thearm lc, as in the form of the invention illustrated in FIG. 2. Thelongitudinal extending portion 7b of the fixing leg 7 and the clampingor fixing area 11 are separated from the contact spring 4 by a deep slot13 formed by an angular cut diverging to the contact spring and a secondcut extending along the edge of the contact spring.

The intermediate or stationary contact 5 carried in the slot 3 of theclamping area 17 is supported outwardly of the clamping area for thecontact springs 4, adjacent the outer end of the base 1 in the slot 3formed in the clamping area 17 and a similar slot formed in aright-angled clamping area 18 formed in a bracket 18a extending alongthe stationary contact for a greater portion of its length. As shown inFIGS. 1 and 4, the stationary contact 5 has a contact leg 14 withcontacts 9a riveted to opposite sides thereof. The contact leg 14 isshorter than the spring leg 6 of the contact spring 4. Said contact 5 isdiagonally slotted by a cut 15, with the right-angled surfaces of saidcontact fixed or clamped to the clamping areas 17 and 18 arranged in agenerally L-shaped or right-angled form.

In order to assure a firm mounting of the contact 5 to the clampingareas 17 and 18, a lug or finger 19 is cut from the fixing-part 16 ofthe contact 5 and may be wedged in the slot 3.

The angular cut 15 in the contact 5 may determine the position of thedesired bending point of the contact leg 14. A hole 20 may also bedrilled through the contact 5 to increase the flexibility of saidcontact particularly along the bending point thereof. The position andsize of the drilled hole may be varied in accordance with therequiredbending point of the contact leg and flexibility thereof. At least twosmall holes may take the place of the large drilled hole 20 toaccommodate the flexibility of the contact 5 and bending point to bereadily adjusted.

The contact springs 4 and 5 have the common advantage that in additionto the right-angled clamping areas and 17 for the inner ends of thespring legs of respective contacts 4 and 5, second right-angled clampingareas 11 and 18 are provided for said respective contacts 4 and 5. Withthis clamping arrangement and the flexibility of the contacts relativeto the clamping areas, the contacts are firmly held in position in thebase and the exact positions of the contacts may be maintained where thecontacts are carried in low depth clamping slots.

A variation of the L-shaped clamping of the contact figures, not shownherein, would be to have fixing or clamping grooves or areas runningparallel to opposite sides of the clamping legs and separated by cuts,like the cuts 13 and 15, extending for portions of the length thereof.

We claim as our invention:

1. In an electrical switching device,

a contact spring set including at least one elongated contact springhaving a contact adjacent its free end and a mounting leg extending toone side of said contact spring,

a relatively stationary flexible contact spring having a contact on itsfree end adapted to be engaged with the contact on the free end of saidelongated contact spring,

means disengaging said contacts and accommodating engagement thereof bythe bias of said elongated contact spring,

a one-piece insulating base and mounting for said contact spring andstationary contact,

said insulating base having separate right-angled clamping areas forsaid mounting legs of said elongated contact spring having clampingareas extending perpendicular to and generally parallel to thestationary and movable contacts and clamping the right-angled edges ofsaid mounting leg for fixing said movable contact to said base andproviding the flexibility of said movable contact to engage anddisengage the contact thereon with the contact of said stationarycontact.

2. The electrical switching device of claim 1, in which terminals extendfrom said mounting leg for said elongated contact spring through theportions of said insulating base forming the clamping areas extendinggenerally parallel to said elongated and generally stationary contactspring sets.

3. The contact spring set of claim 1, in which the clamping areas of themounting leg of the elongated contact spring are to one side thereof andare formed in one piece with the elongated contact spring.

4. The electrical switching device of claim 2, in which elongatedcontact springs are on each side of said stationary contact spring saidstationary contact spring has contacts on opposite sides thereof to bealternately engaged by the contacts of said elongated contact springsand said one-piece insulating base forming a unitary mounting for saidstationary contact spring and said elongated contact springs.

5. The electrical switching device of claim 4, in which the mountinglegs for said elongated contact springs each have a stable L-shapedfixing part having a part secured to extend across the rear end of saidcontact spring, each mounting leg extending parallel to the elongatedcontact spring and having a terminal formed as a part thereof andextending outwardly of said base through the clamping area thereof.

6. The contact spring set of claim 5, in which the mounting leg for thestationary contact also has a terminal extending from its securing partthrough the clamping area of said base extending parallel to saidelongated spring, and secured thereto.

7. The contact spring set of claim 6, in which the base has a clampingslot in advance of and between said clamping slots for said elongatedcontact spring and the stationary contact has a lug bent therefrom andwedged in said clamping slot in advance of said clamping slots for theelongated clamping springs.

8. The contact spring set of claim 6, in which the mounting leg for themovable elongated contact spring has an inclined slot extendingtherealong separating the elongated contact spring from the right-angledmounting leg of said contact, the inner end portion of which defines thebending point of said elongated movable contact spring.

9. The contact spring set of claim 8, in which the mounting leg for theelongated movable contact spring has a hole extending therethroughspaced from and cooperating with said inclined slot to define thebending point of said elongated movable contact spring.

1. In an electrical switching device, a contact spring set including atleast one elongated contact spring having a contact adjacent its freeend and a mounting leg extending to one side of said contact spring, arelatively stationary flexible contact spring having a contact on itsfree end adapted to be engaged with the contact on the free end of saidelongated contact spring, means disengaging said contacts andaccommodating engagement thereof by the bias of said elongated contactspring, a one-piece insulating base and mounting for said contact springand stationary contact, said insulating base having separateright-angled clamping areas for said mounting legs of said elongatedcontact spring having clamping areas extending perpendicular to andgenerally parallel to the stationary and movable contacts and clampingthe right-angled edges of said mounting leg for fixing said movablecontact to said base and providing the flexibility of said movablecontact to engage and disengage the contact thereon with the contact ofsaid stationary contact.
 2. The electrical switching device of claim 1,in which terminals extend from said mounting leg for said elongatedcontact spring through the portions of said insulating base forming theclamping areas extending generally parallel to said elongated andgenerally stationary contact spring sets.
 3. The contact spring set ofclaim 1, in which the clamping areas of the mounting leg of theelongated contact spring are to one side thereof and are formed in onepiece with the elongated contact spring.
 4. The electrical switchingdevice of claim 2, in which elongated contact springs are on each sideof said stationary contact spring said stationary contact spring hascontacts on opposite sides thereof to be alternately engaged by thecontacts of said elongated contact springs and said one-piece insulatingbase forming a unitary mounting for said stationary contact spring andsaid elongated contact springs.
 5. The electrical switching device ofclaim 4, in which the mounting legs for said elongated contact springseach have a stable L-shaped fixing part having a part secured to extendacross the rear end of said contact spring, each mounting leg extendingparallel to the elongated contact spring and having a terminal formed asa part thereof and extending outwardly of said base through the clampingarea thereof.
 6. The contact spring set of claim 5, in which themounting leg for the stationary contact also has a terminal extendingfrom its securing part through the clamping area of said base extendingparallel to said elongated spring, and secured thereto.
 7. The contactspring set of claim 6, in which the base has a clamping slot in advanceof and between said clamping slots for said elongated contact spring andthe stationary contact has a lug bent therefrom and wedged in saidclamping slot in advance of said clamping slots for the elongatedclamping springs.
 8. The contact spring set of claim 6, in which themounting leg for the movable elongated contact spring has an inclinedslot extending therealong separating the elongated contact spring fromthe right-angled mounting leg of said contact, the inner end portion ofwhich defines the bending point of said elongated movable contactspring.
 9. The contact spring set of claim 8, in which the mounting legfor the elongated movable contact spring has a hole extendingtherethrough spaced from and cooperating with said inclined slot todefine the bending point of said elongated movable contact spring.